Salt stress signals shape the plant root

Plants use different strategies to deal with high soil salinity. One strategy is activation of pathways that allow the plant to export or compartmentalise salt. Relying on their phenotypic plasticity, plants can also adjust their root system architecture (RSA) and the direction of root growth to avoid locally high salt concentrations. Here, we highlight RSA responses to salt and osmotic stress and the underlying mechanisms. A model is presented that describes how salinity affects auxin distribution in the root. Possible intracellular signalling pathways linking salinity to root development and direction of root growth are discussed. These involve perception of high cytosolic Na+ concentrations in the root, activation of lipid signalling and protein kinase activity and modulation of endocytic pathways.

► Glycophytes can flexibly adjust their root growth in response to salinity.
► Salt and water stress affect lateral root formation and the direction of primary root growth.
► Salinity-induced effects on root system architecture are mediated by changes in auxin distribution.
► Lipid second messengers and protein kinases modulate vesicular trafficking of auxin efflux carriers.